I brought the ACW's corpse to Guth'Alak, and he gave me a blessed misty potion, which I called "PoCC." A while later, after stashing it, I came back to it with another misty potion (of unknown BUC status), and drank the first potion. It cured a corruption (I think it was mana battery) just fine. But the other misty potion still showed up as a "misty potion," not a "potion of cure corruption." A blessed scroll of identify confirmed that it was indeed a potion of cure corruption.

This seems like a bug since only one type of potion can cure corruptions, just like only one type of scroll can identify/uncursed items and so on.